004Error - Navien NCB-150E Service Manual

Failure mode
Check if there are any
Flame loss and noise
blockages in the gas
occurs at ignition
orifice plate.
Improper air intake air
Rainwater intrusion
supply
Other trouble Defective PCB

5.2.3 004Error

Error occurrence conditions and check items
Error
1. Pre ignition false-flame
If a flame signal is detected continuously for 3 seconds before combustion (stand-by, pre-purge, pre-
ignition), a false-flame error 004E (automatically cleared) is displayed on the front panel and the system
performs continuous post-purge and operates the pump.
E004
False-flame detection
2. Post purge false-flame
If a flame signal is detected continuously for 3 seconds when the system performs post-purge as fuel supply
is stopped, a false-flame error 004E (automatically cleared) is displayed on the front panel and the system
performs continuous post-purge and operates the pump.
1. Check if gas leaks due to defective seals on the main gas valve.
2. Check if proper spark is discharged from the electrode.
Check items
3. Check if gas is supplied within the proper pressure range.
4. Check the PCB and replace if defective.
Cause
Ignition failure will occur if the gas orifices are clogged.
Remove the gas inlet pipe and check the orifice plate.
●
Check if rainwater has collected inside the unit from an improperly installed air intake
pipe.
If the issue continues despite checking above items, replace the PCB.
Is the flame detected in
the burner when there is
no ignition?
Check the current #1 of CN 2: 1 - 20μA
Yes
(see page 18 for Wiring Diagram)
External noise current
Check method
Description
NO
Clean or replace flame rod
Troubleshooting 95